Wheel-mounted vehicle and pneumatic tire for said vehicle

ABSTRACT

A wheel-mounted floating vehicle with superlow pressure tires which creates average ground pressure 0.008-0.009 MPa and does not destroy vegetal soil layer. The ratio of the total mass of the vehicle to the product of the overall diameter (D) of the tire, the section width (B) and the number of wheels fitted with tires ranges between 0.001-0.006 MPa, and the ratio of the mass of each tire to interior volume thereof lies within the limits of 35-80 kg/M3. The radial deflection of the tire with atmospheric interior pressure under the influence of the own mass of the wheel fitted with the tire ranges between 15-45 % of section height (H) of the tire. The interior pressure in the tire varies from 0,005 MPa up to 0,05 MPa. 
     The invention is particularly intended for use in permafrost regions, in the tundra, in swamped areas, in sand deserts as well as in other remote regions.

FIELD OF THE INVENTION

The present invention relates to cross country floating vehicles andpneumatic tyres for such vehicles.

BAGROUND OF THE INVENTION

Wheel-mounted vehicles with pneumatic tyres are known, for which totaldisplacement of wheels fitted with tyres allows them to cross waterobstacles, not resting on bottom (RU No. 2042560, B 62D 61/00, 1995).

Such vehicles work on deformable grounds successfully also with acarrying capacity more than 0.05 MPa without destruction of a vegetalsoil layer. However moving on the grounds with a carrying capacity lessthan 0.05 MPa such vehicles have problems of increase of their crosscountry ability, fuel economy, and also safety of a vegetal soil layerbecause of its considerable deformation.

Carrying capacity of a ground hereinafter is understood to be a contactpressure, at which there is spontaneous subsiding of a ground.

The wheel-mounted vehicles with pneumatic tyres are known also, forwhich total displacement of wheels fitted with tyres allows them tocross water obstacles, not resting on bottom, and the ratio of a mass ofeach tyre to its interior volume varies between 5.0-70.0 kg/m³ (RU No.2084366, B 62D 57/00, B 62D 61/00, 1997).

Such vehicles can work on deformable grounds with a carrying capacitymore than 0.03 MPa without destruction a vegetal soil layer.

However the problems of an increase of cross country ability and fueleconomy, and also safety of a vegetal soil layer remain for thesevehicles on grounds with a carrying capacity 0.03 MPa and less.

The pneumatic tyres containing side walls and ground engaging portionare known, for which the thicknesses of the side walls and of the groundengaging portion are identical and range between 0.01-0.015 of thesection height (RU 2005083, B 60C 5/00, 1993).

Such tyres can work with interior pressure 0.01 MPa and do not ensureaverage pressure in a contact zone with a ground less than 0.02 MPa. Ifinterior pressure in the tyre is less than 0.01 MPa cross folds appearon the thin ground engaging portion of the tyre, which create increasedlocal pressures on the ground destroying a vegetal soil layer. Thereforevehicles with such tyres can work without destruction of a vegetal soillayer only on grounds with a carrying capacity more than 0.03MPa. Movingof the vehicles with such tyres without destruction of a vegetal soillayer is rather problematic on grounds with a carrying capacity 0.03 MPaand less.

Pneumatic tyres containing side walls, ground engaging tread portion anddouble-ply cord carcass are known also, with thickness of the carcass ina ground engaging tread portion and side walls equal 0.003-0.08 ofsection height of the tyre with interior pressure in it 0.01-0.03 MPa.(RU 2042530, B 60C 5100, 5/12, 1995).

If interior pressure is lower 0.01 MPa folds appear on the side walls ofsuch tyres and it promotes an increase of rolling resistance and adeterioration of a controllability of the vehicles.

Therefore while moving with such tyres on grounds with a carryingcapacity 0.03 MPa and less there are problems also of increase of crosscountry ability and safety of a vegetal soil layer, which have not beensoluted in a known level of engineering.

SUMMARY OF THE INVENTION

Object of the invention is the creation of a cross country floatingvehicle capable to work efficiently on deformable grounds with acarrying capacity 0.03 MPa and less without destruction of a vegetalsoil layer, and of a pneumatic tyre for said vehicle working withinterior pressure 0.005 MPa.

This problem is soluted by means of such design relations and parametersof a vehicle and a pneumatic tyre for said vehicle which provideengineering results in the form of increase of cross country ability andfuel economy of the vehicle on deformable grounds with a carryingcapacity 0.03 MPa and less saving a vegetal soil layer, and also in theform of increase of the velocity of its moving on water and facilitationof its moving out of water on coast and ice.

For this purpose in the wheel-mounted vehicle containing the wheelsfitted with pneumatic tyres, the total mass of the vehicle is connectedwith the tyre dimensions by the following relation:${{\frac{M}{D\quad B\quad n}10^{- 5}} = {0.001 - {0.006\quad M\quad {Pa}}}},$

where:

M—total mass of the vehicle, kg

D—overall diameter of the tyre, m

B—section width of the tyre, m

n—number of wheels of the vehicle, and the ratio of a mass of each tyreto its interior volume varies between 35-80 kg/m³.

The number n of wheels in the vehicle equals three or more.

The indicated relation connecting a total mass of the vehicle with thedimensions of the tyre, defines its conventional ground pressure. Thereal ground pressure depends on a total rigidity of the wheels fittedwith pneumatic tyres characterized by the ratio of a mass of each tyreto its interior volume, and defines cross country ability, fuel economyand capacity of the vehicle to move on different grounds withoutdestruction their vegetal soil layer.

Utiltzation of the claimed totality of the essential signs allows toreceive for the vehicle the average ground pressure 0.008-0.009 MPa,that ensures an increase of its cross country ability and a decrease offuel consumption on grounds with a carrying capacity 0.015-0.03 MPasaving their vegetal soil layer, and also an increase of the velocity ofits moving on water and facilitation of its moving out of water on coastand ice.

For solution of the problem in the pneumatic tyre containing side wallsand ground engaging tread portion, the ratio of a mass of the tyre toits interior volume varies between 35-80 kg/M³, and the percent radialdeflection of the tyre with atmospheric interior pressure under theinfluence of its own mass and a mass of the wheel ranges between 15-45%of the tyre section height.

The working interior pressure in the tyre equals 0.005-0.05 MPa.

The tyre section width is more than the tyre section height.

The side walls thickness of the tyre ranges between 0.0025-0.0050 of itsoverall diameter, and the thickness of the ground engaging tread portionvaries between 1.5-2.0 of said side wall thickness.

The pattern of the ground engaging tread portion has recesses and bossesand the latter are distributed on the surface of the ground engagingtread portion uniformly and their height does not exceed 0.015 of theoverall diameter of the tyre, and the ratio of the boss surface area tothe total surface area of the ground engaging porton ranges between0.1-0.2.

The tyre is made of oligomer material.

The tyre contains the cord plies carcass, cords of which form an angleto a meridian of said tyre.

The tyre contains the inner tube.

The ratio of a mass of the tyre to its interior volume defines a totalrigidity of the tyre with the wheel including own rigidity of the tyreand resiliency of air. The average ground pressure in a zone of contactof the tyre with a ground depends on this rigidity mainly when interiorpressure in the tyre is above 0.01 MPa. If interior pressure in the tyreis 0.01 MPa and less its own rigidity is the key factor influencing onthe average pressure in a zone of contact of the tyre with a ground.This rigidity is characterized by a relative radial deflection of thetyre with atmospheric interior pressure under the influence of its ownmass and mass of the wheel.

Utiltzation of the claimed totality of the essential signs of the tyreby the way of limits of parameters describing a total rigidity of thetyre with the wheel and own rigidity of the tyre, ensures the averagepressure in a zone of contact with a ground ranging between 0.008-0.009MPa with interior pressure in the tyre 0.005 MPa.

It allows to increase cross country ability and fuel economy of thevehicle with these tyres moving on grounds with a carrying capacity0.015-0.03 MPa and to save a vegetal soil layer.

If the side walls thickness of the tyre varies between 0.0025-0.0050 ofits overall diameter, and the tyickness of the ground engaging treadportion ranges between 1.5-2.0 of said side wall thickness, it allows todistribute an own rigidity of the tyre along its profile in such a way,that with interior pressure in the tyre 0.005 MPa not only decreasing ofground pressure and its optimum distribution in a zone of contact areensured, but also the stability of the tyre profile shape is maintained.

The side walls thickness of the tyre depends on its overall diameterbecause the latter has a decisive influence on the cross country abilityof the vehicle.

The tread pattern consisting of recesses and bosses, distributed on asurface of the ground engaging tread portion of the tyre uniformly, withrecesses height not exceeding 0.015 of the tyre overall diameter, andwith the the ratio of the boss surface area to the total surface area ofthe ground engaging tread portion equaled 0.1-0.2, promotes uniformground stabilization in a contact zone without its destruction andimprovement of adhesion of tyres.

The application of an oligomer material allows to simplify manufactureof the tyres useing the process of die casting.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

FIG. 1 The vehicle outline.

FIG. 2 The radial section of the tyre with a rim.

FIG. 3 The outline of a cord arrangement in a carcass ply.

FIG. 4 The fragment of a design version of a tread pattern.

FIG. 5 The radial section of the tyre with an inner tube and a rim.

VARIANT OF A REALIZATION OF THE INVENTION

The wheel-mounted vehicle (FIG. 1) contains the body 1 and wheels 2fitted with pneumatic tyres 3. The body 1 can be made faulty sealing,single-volumetric, multi-volumetric, in the form of pick-up, platformetc.

The ratio of the total mass of the vehicle to product of the overalldiameter D (FIG. 2) of the tyre 3, its section width B and number n ofthe wheels 2 fitted with the tyres 3 ranges between 0.001-0.006 MPa, andthe ratio of the mass of each tyre 3 to its internal volume variesbetween 35-80 kg/M³.

The indicated relations in the claimed limits ensure displacement of thewheels 2 fitted with the tyres 3, sufficient for crossing waterobstacles by the vehicle, not resting the wheels on a bottom, withincomplete immersion of the tyres 3 in water, and average groundpressure of the vehicle 0.008-0.009 MPa.

If the ratio of the total mass of the vehicle to product of the overalldiameter D of the tyre 3, its section width B and number n of the wheels2 fitted with the tyres 3 is less 0.001 MPa the arrangement of thevehicle becomes complicated by excessive enlargment of the tyre sizes,or the cargo capacity of the vehicle is reduced at the expense of thesignificant decrease of the total mass.

If this ratio is more 0.006 MPa, the ground pressure increases and thecross country ability and the fuel economy of the vehicle become worseon the deformable grounds with a small carrying capacity.

If the ratio of the mass of the tyre 3 to its interior volume is lessthan 35 kg/ M³ the process of tyres manufacture becomes complicated andthe controllability of the vehicle becomes worse while moving ondeformable grounds with small interior pressure in the tyres 3.

If the ratio of the mass of the tyre 3 to its interior volume is morethan 80 kg /M³ the total rigidity of the wheels 2 fitted with the tyres3 excessively increases and the equipped mass of the vehicle increasesalso, and it causes an increase of the ground pressure and a decrease ofthe cross country ability and fuel economy of the vehicle on deformablegrounds.

In the best version of a realization of the invention with reference toeasy vehicles the ratio of their total mass to product of the overalldiameter D of the tyre 3, its section width B and number n of the wheels2 fitted with the tyres 3 ranges between 0.0030-0.0035 MPa, and theratio of the mass of the tyre 3 to its interior volume —40-45 kg/M³.

Such vehicles not only have high cross country ability, consume a littlefuel, do not destroy a vegetal soil layer moving on deformable groundswith a carrying capacity 0.015 MPa and above, but also have a smalldraught (waterline always is below than axes of the wheels 2). The lastcircumstance promotes a decrease of move resistance and an increase of amove velocity in water at the expense of a decrease of cross section ofthe vehicle units immersed in water. The disposition of the axes of thewheels 2 above water surface facilitates moving the vehicle out of wateron a coast, and while crossing ice-holes in frozen ponds ensures apossibility to catch on the edge of ice by the tyres 3, promoting anindependent moving out of the vehicle on ice.

In the best version of a realization of the invention with reference toheavier passenger and cargo vehicles the ratio of their total mass toproduct of the overall diameter D of the tyre 3, its section width B andnumber n of the wheels 2 fitted with the tyres 3 varies between0.0045-0.0050 MPa, and the ratio of the mass of the tyre 3 to itsinterior volume —45-50 kg/M³.

Interior pressure in the tyres 3 of the vehicle can be reduced up to0.005 MPa, moving on deformable grounds. The average ground pressure ofthe wheels 2 fitted with the tyres 3 ranges between 0.008-0.009 MPa insuch conditions.

The conducted researches reveal, that the ground pressure of the vehicleshould be no more than 0.6 of the ground carrying capacity to ensuresteady moving of the vehicle on a deformable ground and to save vegetalsoil layer. Therefore ground deformations are insignificant, whilemoving with interior pressure in the tyres 3 0.005 MPa even on very weakgrounds with a carrying capacity 0.015-0.03 MPa, and they do not causedestruction of the vegetal soil layer, promoting an increase of adhesionof the tyres 3 and of cross country ability of the vehicle on suchgrounds.

At the same time, with a decrease of work of ground deformation, thevehicle moving resistance is reduced and the fuel consumption fallsaccordingly. The pneumatic tyre 3 (FIG. 2) contains side walls 4, groundengaging portion b, tread 5 and beads 6, fixed on rim flanges 7 of thewheel 2. The interior pressure in the tyre 3 varies between 0.005-0.05MPa. The section width of the tyre B is more than its section height H.

The tyre has a carcass plies 10 , cords 11 of which (FIG. 3) form anangle C to a meridian 12. An angle C in a crosspoint of a meridian 12 ofthe tyre with its equator 13 ranges between 50-60 degrees. That anglecan be 0 degrees in a specific case. The cord can be made of polyamid,viscose and other materials. The ratio of a mass of the tyre 3 to itsinterior volume varies between 35-80 kg/M³. Interior volume of the tyre3 is understood to be a volume confined to an interior surface of thetyre 3 and by surface of the rim 7 turned into it. Interior volume ofthe tyre 3 can be defined by the following way. The wheel 2 assembledwith the tyre 3, and separately the tyre 3 and the wheel 2 with units ofthe rim 7 are immersed into a bath of water sequentially. A volume ofdisplaced water is stated every time. The difference between the volumeof water displaced by the wheel 2 assembled with the tyre 3 and the sumof the volumes of water, displaced separately by the tyre 3 and thewheel 2 with units of the rim 7, corresponds to an interior volume ofthe tyre 3.

Tyre deflection ranges between 15-45% of the tyre section height H whileloading the tyre with a radial load equaled to own mass of the wheel 2fitted with the tyre 3 and atmospheric interior pressure in the tyre 3.

The percent tyre deflections in claimed limits characterize an ownradial rigidity of the tyre 3, which provide a contact surface with aground sufficient for the average ground pressure to be 0.008-0.009 MPawhen interior pressure in the tyre 3 is 0.005 MPa. If percent tyredeflections of the tyre 3 with atmospheric interior pressure under theinfluence of the own mass of the wheel 2 fitted with the tyre 3 are lessthan 15% , radial rigidity of the tyre 3 has such a value that a contactsurface with a ground remains constant while lowring pressure in thetyre 3 below 0.01 MPa. The cross country ability of the vehicle withsuch tyres 3 is reduced on grounds with a carrying capacity 0.3 MPa andless. If percent tyre deflections of the tyre 3 with atmosphericinterior pressure under the influence of the own mass of the wheel 2fitted with the tyre 3 are more than 45% , radial rigidity of the tyre 3is so small, that the latter loses a profile stability when interiorpressure is less 0.01 MPa. The vehicle controllability becomes worse inthese conditions.

The tread pattern of the tyre 5 (FIG.) has bosses 8 and recesses 9. Thebosses 8 distributed on a surface of the ground engaging portion buniformly, and their height m does not exceed 0.015 D. The ratio of theboss surface area to the total surface area of the ground engagingportion b varies between 0.1-0.2. If the ratio is less than 0.1,pressure on the bosses 8 increases and their wear rises on a rigid road.If the ratio is more than 0.2 adhesion of the tyre deteriorate.

The thickness α of the side walls 4 of the tyre ranges between0.0025-0.0050 of its overall diameter D, and the thickness k of theground engaging portion b up to the base of the bosses 8 of the treadpattern 5 varies between 1.5-2.0 of the thickness α of the side walls.

If the thickneeses α of the side walls and k of the ground engagingportion are performed in claimed limits, own rigidity of the tyre 3 isdistributed to the tyre profile in such a way, that stability of thetyre profile remains and the optimum distribution of the groundpressures in a contac zone is ensured with falling of interior pressurein the tyre 3 up to 0.005 MPa.

If the thickness α of the side walls 4 is less than 0.0025D, folds canappear on them when interior pressure in the tyre less than 0.01 MPa,that sharply increases rolling resistance of the tyres 3 and make worsea controllability of the vehicle.

If the thickness α of the side walls 4 is more than 0.005D, the radialdeflection of the tyre 3 remains permanent practically when interiorpressure in the tyre falls from 0.01 MPa up to 0.005 MPa, and the groundpressure is 0.015 MPa and above. In these conditions cross countryability of the vehicle on grounds with a carrying capacity less 0.03 MPais reduced and the fuel consumption rise.

Realisation of the thickness k of the ground engaging portion b lessthan 1.5 a, promotes irregular ground pressure distribution wheninterior pressure in the tyre 3 less than 0.01 MPa. In this case movingof the vehicle on grounds with a carrying capacity less 0.03 MPa isaccompanied by significant ground local deformations which causedestruction of the vegetal soil layer, lowering of cross country abilityand increase of fuel consumption.

An increase of the thickness k of the ground engaging portion b of thetyre 3 more than 2 a makes worse its ability “to adapt” to groundirregularities comparable on a size to the tyre profile when interiorpressure is less than 0.01 MPa, that reduces cross country ability ofthe vehicle on grounds with a small carrying capacity. At the same time,while moving on hard roads, the hysteresis losses in the ground engagingportion b of the tyre 3 increase in this case and fuel consumptionincrease accordingly.

The tyre 3 contains the inner tube 14 (FIG. 5).

In the best version of a realization of the invention:

the ratio of the mass of the tyre 3 to its interior volume rangesbetween 40-50 kg/M³ from the claimed range 35-80 kg/M³;

the relative radial deflection of the tyre 3 with atmospheric internalpressure varies between 17-30% from the claimed range 15-45%

Industrial Applicability

The floating cross country vehicle and the pneumatic superlow pressuretyre for it can be used most efficiently in regions in permafrostregions, in the tundra, in swamped areas, in sand deserts as well asother remote regions. They also can cross afloat easily small ponds andmove on usual roads. Key feature of such vehicles is that their effecton a ground allows to keep vegetal soil layer undamaged.

We claim:
 1. A wheel mounted vehicle containing wheels (2) fitted withpneumatic tyres (3), wherein a total mass of the vehicle is connectedwith the dimensions of said tyres (3) in accordance with the followingrelation:${{\frac{M}{D\quad B\quad n}10^{- 5}} = {0.001 - {0.006\quad M\quad {Pa}}}},$

where: M is the total mass of said vehicle, kg D is an overall diameterof said tyre, m B is a section width of said tyre, m n is a number ofwheels of said vehicle and the ratio of a mass of each said tyre (3) toan interior volume of said tyre varies between 35-80 kg/M³.
 2. The wheelmounted vehicle according to claim 1 wherein, said number n of wheels is3 or more.